Conventionally, various sound absorbing panels are proposed. For example, the following Patent Literature 1 discloses a stacked body excellent in sound absorbency and fireproof performance by stacking a glass cloth on one surface of a punching metal.
The following Patent Literature 2 discloses the technology that absorbs sound noise inside the cabin by employing glass wool, sponge, and foamed resin stacked between two punching metals as a cover of the baggage rack in a railway vehicle.